1. Field of the Invention
The present invention relates to a radar device, and more particularly to a radar device that can detect not only an object but also dirt that is adhered to a radome of an antenna on the basis of a reflected signal.
2. Description of the Related Art
As a conventional radar device, there has been proposed an FM radar device that extracts a low frequency component of a beat signal by a low pass filter, performs the extracted low frequency component to A/D conversion by an A/D converter, performs fast Fourier transformation by a fast Fourier transformer, and compares frequency spectrum data, in which a low frequency component in a state where no dirt is adhered to a radome is stored, with inputted frequency spectrum data of a low frequency component to detect that dirt is adhered to the radome (for example, refer to JP 10-282229A).
Also, as another conventional radar device, there has been proposed a radar device that provides another detection threshold value for road surface detection which is different from a normal detection threshold value, and determines that dirt is adhered to the radome in the case where the number of occurrences of the beat signals which exceed the detection threshold value for road surface detection within a given period of time is equal to or smaller than a given value (for example, see JP 2000-019242B)